DE 34 02 603 A1 teaches such suction cleaner in the form of a vacuum cleaner wherein a jacket of a sound absorbing foam material is provided around the motor, wherein flow openings are provided that extend radially sideways relative to the motor. Therefore the outside of the silencing jacket is provided with flow passages that extend along the inside of the motor housing and which convey the flow of air axially along the outside of the jacket and the blower and to an outflow opening arranged at the blower with a view to concentrating the flow of air from the vacuum cleaner.
GB A 2 062 451 also teaches a suction cleaner in the form of a vacuum cleaner and having around the motor a jacket of a silencing material. Outside this jacket a further jacket is arranged which is spaced from the innermost jacket by means of studs whereby a number of interconnected flow paths are provided which extend partially axially relative to the rotational axis of the motor. This prior art suction cleaner is associated with the problem that the flow passages which are covered by the jackets and the activated studs give rise to a fairly turbulent flow pattern with ensuing large friction losses.
The vacuum cleaner according to DE 34 02 603 A1 distinguishes itself over other known types by the jacket enclosing the motor being of a silencing material, such as foamed plastics, whereby the jacket is self-supporting and does not have to be braced as is the case with other types of vacuum cleaners, such as e.g. the vacuum cleaner according to U.S. Pat. No. 5,293,664 or DE C 64 13 71 wherein the jacket is of a silencing material applied as a surface coating on a relatively rigid jacket-shaped element in combination with the radially arranged flow passages resulting in a relatively small friction loss in the flow. By the substantially self-supporting jacket according to DE 34 02 603 A1 a reduction of the sound transmission through rigid elements in the structure of the vacuum cleaner is further obtained while simultaneously providing a silencing jacket which is comparatively simple and inexpensive to manufacture.